Linux Plumbers Conference 2021

Session

Real-time MC

21 Sept 2021, 07:00

Description

The Real-time microconference focuses on finishing the last lap of getting the PREEMPT_RT patch set into mainline. Many of these missing pieces, however, are not at the core of real-time features (like locking, and scheduling), but instead, on other subsystems that compose the kernel, like file systems and memory management. Making this Linux subsystems compatible with PREEMPT_RT requires finding a solution that is acceptable by subsystem maintainer, without having these subsystems suffer from performance or complexity issues.

224. Maintaining PREEMPT_RT: now and then

Sebastian Andrzej Siewior (Linutronix)

21/09/2021, 07:05

This topic will present the current workflow for maintaining the PREEMPT_RT, and
discuss the challenges of maintaining the PREEMPT_RT mode when the merge is done.

167. rtla: an interface for osnoise/timerlat tracers

Daniel Bristot de Oliveira (Red Hat, Inc.)

21/09/2021, 07:40

The osnoise and timerlat tracers landed up in 5.14.

In addition to the tracing aspects, these two tracers also report performance metrics relevant to real-time. However, it is not easy to manually parse these metrics.

The rtla (real-time linux analysis) is a user-space interface for these tracers. It works by using the libtracefs to set up a tracing section and to collect data and trace...

228. Linux kernel support for kernel thread starvation avoidance

Sharan Turlapati, Srivatsa Bhat (VMware)

21/09/2021, 08:25

ABSTRACT

Running CPU-intensive high-priority real-time applications on a
real-time Linux kernel (based on the PREEMPT_RT patchset) can lead to
situations where the kernel's own housekeeping tasks such as per-cpu
kernel threads get starved out, resulting in system instability
(hangs/unresponsive system). The Real-Time Throttling feature in the
Linux kernel is ineffective in...

101. Next steps for futex2

André Almeida (Collabora)

21/09/2021, 09:00

The community has an agreement that a new futex syscall is needed to add new features to help with performance and scalability issues. However, after some patches proposed with different implementations approaches, the path to get it merged is not clear. The goal of this session is to get maintainers and developers together to figure out which is the best approach to make progress in the new interface.

213. printk: kthreads and atomic consoles for mainline

John Ogness (Linutronix GmbH)

21/09/2021, 09:50

Since 2018 there has been a dedicated effort to rework printk. Originally fueled by the need to make printk real-time friendly, the task quickly evolved to address many other existing problems within the printk subsystem. Since 5.8 there has been a steady flow of these improvements getting merged into mainline, but several RT-critical pieces are still remaining: sync mode, kthread printers,...

168. PREEMPT_RT: status and Q&A

Thomas Gleixner

21/09/2021, 10:25

In this talk, Thomas Gleixner will present the status of the PREEMPT_RT, along
with a section of questions and answers regarding the upstream work and the
future of the project.

17. Real-time Microconference

Since 2004 a project has improved the Real-time and low-latency features for Linux. This project has become know as PREEMPT_RT, formally the real-time patch. Over the past decade, many parts of the PREEMPT RT became part of the official Linux codebase. Examples of what came from PREEMPT_RT include: Mutexes, high-resolution timers, lockdep, ftrace, RT scheduling, SCHED_DEADLINE, RCU_PREEMPT,...